The Internet is composed of a large number of smaller, interconnected networks. Each of these networks potentially connects a large number of systems to the Internet. These systems may be personal computers, servers, or other devices with internet compatibility.
There are a number of different networks that use the infrastructure of the Internet: internets, intranets, darknets, peer to peer networks, etc. Internets are generally public access networks, freely accessible by anyone with access to the Internet. Intranets are restricted access networks, allowing only a pre-specified group of users access to the information therein. Darknets are a category of network that allow communication between users without allowing others to access the content being communicated.
The most common relationship on the Internet is the client-server relationship. In this arrangement, a number of servers store and maintain information that is accessible by clients. Users obtain access to the Internet and access those servers, communicating either by upload (sending information to a server) or download (receiving information from a server). An alternative arrangement is a peer to peer network. Peer to peer networks (i.e. client to client networks) rely on the individual client systems connected to the internet for storage and transfer, rather than servers. The term “peer to peer” describes the nature of such a network, a network in which every user contributes both to the storage/transfer of information as well as the retrieval of information. Users in a peer to peer network typically originate at an equal level with other users, but may organize themselves into a hierarchical arrangement. Different arrangements may be formed for different functions, i.e. when a network is used for searching the users may take one form of hierarchy, likewise when a network is used for data transfer. Regardless of the structure, users in a peer to peer network communicate directly with each other rather than communicating through an intermediary server.
There are a number of different peer to peer networks. Some are built on Internets, some are built on darknets, and yet others are built on intranets. Because of the proliferation of these networks, there are a number of different protocols for communication between users in a peer to peer network. To access any of these networks, a user needs to understand the protocol of that particular network.